Oxygen Vacancy Kinetics Mechanism of the Negative Forming-Free Process and Multilevel Resistance Based on Hafnium Oxide RRAM

Mingqun Qi,Cuiping Guo,Meihan Zeng

doi:10.1155/2019/6724018

Mingqun Qi, Cuiping Guo + Show 1 more

Open Access

https://doi.org/10.1155/2019/6724018

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Abstract

Switching between high resistance states and low resistance states in a resistive random access memory device mainly depends on the formation and fracture of conductive filaments. However, the randomness of the conductive filament growth and the potential breakdown of the large voltage in the forming process will lead to unstable resistive switching and memory performance. We studied the possible natural forming process of conductive filaments for intrinsic defects under the influence of top electrode material based on the structure of W/HfO2-x/Pt. Such a simple device shows long retention time and great endurance cycles. The dendritic oxygen vacancy (VO) conductive filament model was constructed, and the dynamic VO migration under directional external bias was described according to the characteristic electrical performance. In addition, we also explored the relationship between the multilevel resistance and the evolution of a dendritic VO conductive filament, signifying the potential application of multilevel storage in the future. Furthermore, a Ag/HfO2-x/Ag selector was fabricated to assemble the memory device in wire connection which exhibits the potential of eliminating leaky current in the memory array. The connection also indicates that the fabrication process of the 1S1R structure can be simplified by using the same functional layer.

Highlights

With the advent of the big data era, the explosive amount of information requires researchers to constantly seek for memory such as high-speed operation, large on/off ratio, reliable switching endurance, long high-temperature lifetime, multivalue storage, and high device yield [1]
In the negative sweeping process, the resistance of the device changes from a low resistance state (LRS) to a high resistance state (HRS) indicating the intrinsic formation of VO conductive filaments (CFs) from bottom to top
Before sputtering Pt electrode, in order to enhance the binding force of the film and the silicon substrate, we first sputter on the silicon substrate with titanium which has better binding force both with silicon substrate and Pt electrode

Summary

Introduction

With the advent of the big data era, the explosive amount of information requires researchers to constantly seek for memory such as high-speed operation, large on/off ratio, reliable switching endurance, long high-temperature lifetime, multivalue storage, and high device yield [1]. In the negative sweeping process, the resistance of the device changes from a low resistance state (LRS) to a high resistance state (HRS) indicating the intrinsic formation of VO conductive filaments (CFs) from bottom to top.

Results

Conclusion